"The Attorney General's Office found that AOL conducted billions of auctions for ad space on hundreds of websites the company knew were directed to children under the age of 13," Underwood's announcement said. "Through these auctions, AOL collected, used, and disclosed personal information from the websites' users in violation of COPPA [Children's Online Privacy Protection Act], enabling advertisers to track and serve targeted ads to young children."

In addition to paying the largest-ever fine for violating COPPA, the Verizon-owned company "has agreed to adopt comprehensive reforms to protect children from improper tracking," the announcement said.